I am thinking in terms of the Dollar being the world's reserve currency. There probably is more to factor in but Any currency's value is based on what it can buy. Which is perceived by its scarcity. With currency everything is relative to everything else. Since the dollar is the world reserve currency it is just he easiest to compare to.

Let me give you an example of what I mean. 2009 to 2012 the stock market rose substantially in dollar terms. However so did the price of gold. In fact the stock market and the price of gold tracked perfectly during that time. Which means that the Stock market did not really go up as much as the value of the dollar went down due to the pumping of dollars into the economy by the federal reserve.

Now I said $57 is the value of Bitcoin is relatively based on the amount of US currency in circulation. Another way to measure is the amount of US government debt + the amount of US currency in circulation. Which would be around $21 Trillion. Plus not all 21 billion Bitcoins have been mined. But for simplification assume all have been mined. That would put the "Natural" value of Bitcoins at $1000 relative to the dollar. IE the long term average if the amount of dollars stays the same.

The most likely reason Bitcoin's value is above these amounts is emotional(Deflation). The second is it is a pump and dump. I discount the latter because there are individuals with huge piles of bitcoin they have bought years ago and never sold. Which adds another problem: The volume of Bitcoins being bought and sold is going down since as Bitcoins become more valuable fewer are needed to buy things. Which is deflation and a bad thing for Bitcoin. Currencies that have a stable value are much more preferable But as it is BItcoins is in a closed feedback loop. There is a maximum of $21 billion coins. As the value goes up people are less likely to sell and much more likely to buy. Which drives the value up radically. At some point there is a danger of a Bitcoin collapse.

South Korea has been ground zero for a global surge in interest in bitcoin and other digital currencies as prices surged this year, prompting the nation’s prime minister to worry over the impact on Korean youth. While there’s no indication Asia’s No. 4 economy will shutter exchanges that have accounted by some measures for more than a fifth of global trading, the news is a warning as regulators express concerns about private digital currencies.